The disclosure relates to gas turbine engines. More particularly, the disclosure relates to fire containment coatings for titanium components.
In gas turbine engines, compression of inlet air causes a continuous temperature and pressure increase from upstream to downstream along the gaspath within the compressor section(s). Components within the compressor section(s) are typically made of lightweight alloys such as titanium alloys. Such components include disks, blade stages carried by the disks, case structure surrounding the disks, vane stages carried by the case structure between blade stages, and outer air seals carried by the case structure surrounding the blade stages.
The high temperature and air pressure within downstream portions of the compressor section(s) create a favorable environment for engine fires. Blade tip rub against outer air seals may be sufficient to ignite titanium material of the blades and/or air seals. This material may be driven into contact with the case structure. To contain fires, the inner diameter (ID) portions of the case structure may be coated with a barrier coating system similar to those used on hot section components (e.g., used on nickel-based superalloy components of combustor and turbine sections). Exemplary coatings comprise a metallic bondcoat and a ceramic barrier coating. The barrier coating provides thermal insulation. Exemplary bondcoats are MCrAlY bondcoats. Exemplary barrier coatings are zirconia-based (e.g., yttria-stabilized zirconia).